LT1 $EE tuning for E10

[Terminal_Crazy]

Hi guys,
after losing my post I just typed out, I'll keep this brief.

What do I need to alter on $EE to go from E0 to E10 fuel.
Running 95 LT1 383 CL SD No MAF
My WB reads in AFR and the 12.8 target should be about 12.3 on E10. 0.96 correction factor for E10
Do I just increase the PE correction tables.

Anything else I should change like OL AFR target?


Also, how would i richen the cruise area. 1k-2k rpm 60-80 map.
VE tables just tune themselves back out.
Would raising the O2 swing voltages help here, By how much ?

TIA
Cheers
Mitch

[ralmo94]

Stioch for E10 is about 14.1:1,
100% gas 14.7:1
Wide band only reads lambda and represents it in AFR scale of 100% gas
The essiest way is to adjust commanded PE Afr to get desired reading on Wide band
Assuming already in tune.

Hope that makes sense

[Terminal_Crazy]

Stioch for E10 is about 14.1:1,
100% gas 14.7:1
Wide band only reads lambda and represents it in AFR scale of 100% gas
The essiest way is to adjust commanded PE Afr to get desired reading on Wide band
Assuming already in tune.

Hope that makes sense

Yeah, that's what i'm doing.

If it's running stoich on E0 the WB will be showing 14.7
If i then switch to E10, at stoich the WB will still read 14.7 yes?
At WOT I'd want to target 12.3 though.

What about the OL AFR Tables, would I scale those as well?

Thanks
Mitch

[ralmo94]

Yeah, that's what i'm doing.

If it's running stoich on E0 the WB will be showing 14.7
If i then switch to E10, at stoich the WB will still read 14.7 yes?

Correct. This is a subject that can be very complicated and confuse a lot of people, but it doesn't have to.
If you think of AFR as the recipe the computer uses to get the final lambda reading in the exhaust.
All oxygen sensors can read is the lambda of the exhaust. Stoich.
They don't read the the recipe that gets it that way. Lambda 1 is stoich. It is only expressed in AFR to be easily understood.
E10 stoich recipe is 14.1 = lambda 1
E0. Stoich recipe is 14.7 = lambda 1

I'm not familiar with EE, but the proper way to do it, is to change the stoich AFR value in the computer from 14.6 or 14.7 to 14.1.
But if the open loop tables still are referenced in AFR they still would need to be scaled as well.
To find what AFR is in lambda AFR divided by stoich AFR.
EXAMPLE
13afr divided by 14.7 stoich = 0.88 lambda
13afr divided by 14.1 stoich = 0.92 lambda

0.92 lambda multiplied by 14.7 stoich is 13.5 AFR.
So if you have a reading on the wideband of 13 AFR, the lambda is 0.88
The recipe to get it is different for different stoich fuels

So the easiest way, is adjusting the commanded AFR until you get the desired reading on the wideband,

Did I confuse anyone yet?

[steveo]

for E10 i just fudge the injector constant by 4-5% of enrichment. that'll cover everything.

[ralmo94]

for E10 i just fudge the injector constant by 4-5% of enrichment. that'll cover everything.

That sounds easy and quick
Is the constant the lb per hr?

[steveo]

yeah. you can always scale the injector constant to add or subtract fuel everywhere at the same time. it is a pure base constant that all calculations use.

[Terminal_Crazy]

Many thanks Steveo.

[NomakeWan]

While we're on the subject, what exactly do the "AFR Target" tables do in $EE? We only have narrowband O2 sensors, so it can't be querying a wideband for precise AFRs. So what are these tables referencing as AFR?

[ralmo94]

While we're on the subject, what exactly do the "AFR Target" tables do in $EE? We only have narrowband O2 sensors, so it can't be querying a wideband for precise AFRs. So what are these tables referencing as AFR?

Not EE specific, but an open loop table is used when open loop. While open loop, the loop to the O2 sensor is not used, such as warm up, PE, Decel cut off, or O2 error. Some tunes have the table enabled during closed loop for sort of a lean cuise, anytime anything other than stoich is targeted, you are open loop

[NomakeWan]

Not EE specific, but an open loop table is used when open loop. While open loop, the loop to the O2 sensor is not used, such as warm up, PE, Decel cut off, or O2 error. Some tunes have the table enabled during closed loop for sort of a lean cuise, anytime anything other than stoich is targeted, you are open loop

Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

[ralmo94]

Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

That is what the VE table or MAF table is for, O2 is just for correction

[ralmo94]

To be more specific, fueling is based on airflow, how much air is going in the engine.
Knowing how much air is going in, the pcm can calculate how much fuel is needed.

The ratio is how many part of air to one part fuel
AFR

Air to Fuel Ratio
If we we are taking in so many lbs of air, we need so many lbs of fuel to mix the ratio.

Does that make sense?

[steveo]

Sure, but that doesn't answer the question. Without the ability to have any kind of precise AFR feedback, how is the PCM "targeting" a specific AFR? What is $EE using to determine AFR if not a lambda sensor?

most ecms work like this

1. you have an airflow measurement, either with a MAF or speed density (a volumetric efficiency map, in other words a chart that says 'in this condition the engine flows this much air')

2. you have the fuel flow metrics, that end up calculating something like 'if you open the injector for this long, this much fuel comes out'

3. you then try to hit your AFR target vs airflow vs injector metrics to figure out how much fuel to inject

this is both in open loop and closed loop.

there are auxiliary calculations like closed loop trims, transitional fuel needs like accel enrichment, and some other small calculations and constants, but those modify things in the above three steps. without step three, you aren't going anywhere.

in other words, without step three, how would you know that you don't inject one part air for one part fuel?

[ralmo94]

Good in depth simple explanation stevo. I hope he understands.
I think there are a lot of people who think fuel control is from O2 sensor only.